System and method for treating ischemic stroke

ABSTRACT

A thromboembolic removal system for treating ischemic stroke, including a guide and occlusion catheter, a delivery and aspiration catheter, an aspiration pump, a thromboembolic receiver, and a thromboembolic separator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/253,242 (Attorney Docket No. 41507-703.501), filed Oct. 5, 2011, nowU.S. Pat. No. ______, the entire content of which are incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates generally to the field of medicaltreatment and, more particularly, to a system and method for treatingischemic stroke which involves removing a thromboembolism from acerebral artery of a patient.

BACKGROUND

Stroke is a leading cause of death and disability and a growing problemto global healthcare. In the US alone, over 700,000 people per yearsuffer a major stroke and, of these, over 150,000 people die. Even moredisturbing, this already troubling situation is expected to worsen asthe “baby boomer” population reaches advanced age, particularly giventhe number of people suffering from poor diet, obesity and/or othercontributing factors leading to stroke. Of those who a survive stroke,approximately 90% will suffer long term impairment of movement,sensation, memory or reasoning, ranging from mild to severe. The totalcost to the US healthcare system is estimated to be over $50 billion peryear.

Strokes may be caused by a rupture of a cerebral artery (“hemorrhagicstroke”) or a blockage in a cerebral artery due to a thromboembolism(“ischemic stroke”). A thromboembolism is a detached blood clot thattravels through the bloodstream and lodges in a manner that obstructs oroccludes a blood vessel. Between the two types of strokes, ischemicstroke comprises the larger problem, with over 600,000 people in the USsuffering with ischemic stroke per year.

Ischemic stroke treatment may be accomplished via pharmacologicalelimination of the thromboembolism and/or mechanical elimination of thethromboembolism. Pharmacological elimination may be accomplished via theadministration of thrombolytics (e.g., streptokinase, urokinase, tissueplasminogen activator (TPA)) and/or anticoagulant drugs (e.g., heparin,warfarin) designed to dissolve and prevent further growth of thethromboembolism. Pharmacologic treatment is non-invasive and generallyeffective in dissolving the thromboembolism. Notwithstanding thesegenerally favorable aspects, significant drawbacks exist with the use ofpharmacologic treatment. One such drawback is the relatively long amountof time required for the thrombolytics and/or anticoagulants to takeeffect and restore blood flow. Given the time-critical nature oftreating ischemic stroke, any added time is potentially devastating.Another significant drawback is the heightened potential of bleeding orhemorrhaging elsewhere in the body due to the thrombolytics and/oranticoagulants.

Mechanical elimination of thromboembolic material for the treatment ofischemic stroke has been attempted using a variety of catheter-basedtransluminal interventional techniques. One such interventionaltechnique involves deploying a coil into a thromboembolism (e.g. viacorkscrew action) in an effort to ensnare or envelope thethromboembolism so it can be removed from the patient. Although animprovement over pharmacologic treatments for ischemic stroke, suchcoil-based retrieval systems have only enjoyed modest success(approximately 55%) in overcoming ischemic stroke due to thromboembolicmaterial slipping past or becoming dislodged by the coil. In the lattercase, the dislodgement of thromboembolic material may lead to anadditional stroke in the same artery or a connecting artery.

Another interventional technique involves deploying a basket or netstructure distally (or downstream) from the thromboembolism in an effortto ensnare or envelope the thromboembolism so it can be removed from thepatient. Again, although overcoming the drawbacks of pharmacologictreatment, this nonetheless suffers a significant drawback in that theact of manipulating the basket or net structure distally from theoccluded segment without angiographic roadmap visualization of thevasculature increases the danger of damaging the vessel. In addition,removing the basket or net structure may permit if not causethromboembolic material to enter into connecting arteries. As notedabove, this may lead to an additional stroke in the connecting artery.

A still further interventional technique for treating ischemic strokeinvolves advancing a suction catheter to the thromboembolism with thegoal of removing it via aspiration (i.e. negative pressure). Althoughgenerally safe, removal via aspiration is only effective with relativelysoft thrombus-emboli. To augment the effectiveness of aspirationtechniques, a rotating blade has been employed to sever or fragment thethromboembolism, which may thereafter be removed via the suctioncatheter. While this rotating blade feature improves the effectivenessof such an aspiration technique, it nonetheless increases the danger ofdamaging the vessel due to the rotating blade.

The foregoing interventional techniques, as well as others in the priorart, all suffer one or more drawbacks and are believed to be sub-optimalfor treating ischemic stroke. The present invention is directed atovercoming, or at least improving upon, the disadvantages of the priorart.

When such an obstruction occurs in a cerebral vessel, the result is astroke and potential cell death soon thereafter. The resulting symptomsof immobility and/or loss of function depend upon the location of theocclusion within the cerebrovasculature, and the severity of impact ofischemic stroke is directly related to the length of time blood flow isoccluded in a particular cerebral vessel. Specifically, regardless ofthe means of complete removal of a thromboembolism, a common urgencyremains: to restore blood flow through the vessel as soon as possibleafter occlusion in order to minimize cell death during the acute phaseof stroke, (and/or during the initial treatment of a patient) whilephysicians determine the desired course of treatment for permanent andcomplete elimination of the embolism. It is an object of the inventionherein to provide a means for temporarily restoring blood flow through ablocked cerebral vessel, prior to and/or during the procedures to morepermanently and completely remove the blockage, and to permanently andcompletely remove the blockage. It is a further object of the inventionto remove embolic material from the vessel. It is a further object ofthe invention to provide a device that can be readily tracked throughthe tortuous and fragile anatomy of the cerebrovasculature. It is afurther object of the invention to provide a device that will loadreadily into a delivery catheter, will deploy readily within thecerebrovasculature at the site of an occlusion, and will be readilyremovable via the delivery catheter following restoration of sufficientblood flow. It is a further object of the invention to permit thedelivery and deployment of additional therapies (such as, for example,disruption and aspiration of the embolism) during use of the device.

In a first aspect, the present invention provides a system for removingthromboembolic material from a blood vessel. The system includes anelongate catheter proportioned for insertion into a blood vessel, wherethe catheter has a lumen extending therethrough. An elongate member ismounted to extend and retract through the lumen, and an expandable andcollapsible separator element is disposed at a distal end of theelongate member. The separate element comprises a plurality of uprightsand a multiplicity of apexes extending between said uprights, wherein atleast some of the uprights and a first group of apexes are disposedabout a central longitudinal axis of the separator and a second group ofthe apexes extend inwardly toward the central longitudinal axis of theseparator.

In a second aspect, the present invention provides a method ofmanufacture of a system for removal of thromboembolic material from ablood vessel. The method comprises the steps of cutting a plurality ofuprights and apexes from a length of tubing to form a separator elementadjoining some of the apexes to one another, and mounting said separatorelement to an elongate element.

In a third aspect, the present invention provides a method of removal ofthromboembolic material from a blood vessel of a subject. The methodcomprises the steps of introducing into the vessel proximate thethromboembolic material an elongate member having an expandable andcollapsible separator element disposed at a distal end of the elongatemember. The separator element comprises a plurality of uprights and amultiplicity of apexes extending between said uprights, wherein at leastsome of the uprights and a first group of apexes are disposed about acentral longitudinal axis of the separator and a second group of theapexes extend inwardly toward the central longitudinal axis of theseparator.

BRIEF DESCRIPTION OF THE DRAWINGS

Many advantages of the present invention will be apparent to thoseskilled in the art with a reading of this specification in conjunctionwith the attached drawings, wherein like reference numerals are appliedto like elements and wherein:

FIG. 1 is a partial sectional side view of one embodiment of athromboembolic removal system, including a guide and occlusion catheter,a delivery and aspiration catheter, an aspiration pump, a thromboembolicreceiver, and a thromboembolic separator;

FIG. 2 is a partial sectional side view of a delivery and aspirationcatheter forming part of the thromboembolic removal system shown in FIG.1, illustrating a thromboembolic receiver element in an undeployedstate;

FIG. 3 is a partial sectional side view of a delivery and aspirationcatheter forming part of the thromboembolic removal system shown in FIG.1, illustrating the thromboembolic receiver element in a deployed state;

FIG. 4A is a perspective view depicting an alternate embodiment of athromboembolic receiver, equipped with a plurality of engagementelements.

FIG. 4B is a cross section view taken along the plane designated 4B-4Bin FIG. 4A.

FIG. 4C is a perspective view illustrating the distal portion of thethromboembolic receiver of FIG. 4A.

FIG. 5 is a plan view of the alternate thromboembolic receiver of FIG.4. Although the receiver is preferably a tubular structure, FIG. 5 showsit opened and flattened into a sheet so that its features may be moreeasily viewed;

FIG. 6 is a top view illustrating one embodiment of a flex region foruse in flexibly coupling the thromboembolic receiver, such as thereceiver of FIG. 4A, to an elongate member or a delivery and aspirationcatheter;

FIG. 7 is a perspective view of an alternate thromboembolic receiver,equipped with a plurality of engagement elements capable of beingselectively deployed after the deployment of the thromboembolicreceiver.

FIG. 8A is perspective view of a thromboembolic receiver having featuresfor facilitating reloading of the receiver into a catheter.

FIG. 8B is a plan view similar to the view of FIG. 5 showing thethromboembolic receiver of FIG. 8A.

FIG. 8C is a perspective view of a proximal portion of thethromboembolic receiver of FIG. 8A and the distal portion of theelongate member coupled to the thromboembolic receiver, illustratingretraction of the thromboembolic receiver into a delivery and aspirationcatheter.

FIGS. 9 and 10 are partial sectional side views of one embodiment of athromboembolic disrupter or separator in use with a delivery andaspiration catheter.

FIG. 11A is an enlarged view of the separator element forming part ofthe thromboembolic separator shown in FIGS. 9 and 10.

FIG. 11B is a side elevation view of an alternate embodiment of athromboembolic separator.

FIG. 11C is an enlarged view of the separator element forming part ofthe thromboembolic separator shown in FIG. 11B.

FIG. 11D is a side elevation view similar to FIG. 11C showing anotheralternate embodiment of a thromboembolic separator.

FIG. 12 is a partial sectional view of a patient illustrating thethromboembolic removal system of FIG. 1 in use within the arterialsystem.

FIG. 13 is a partial sectional view of a patient illustrating the distalregion of the thromboembolic removal system of FIG. 1 in use within acerebral artery.

FIG. 14 is a partial section side view illustrating advancement of aguide wire to a thromboembolism.

FIG. 15 is a partial section side view illustrating advancement of theguide and occlusion catheter, with the balloon in a deflated state.

FIG. 16 is a partial section side view illustrating inflation of theballoon occlusion member to arrest the blood flow within the arterycontaining the thromboembolism.

FIG. 17 is a partial section side view illustrating the step ofadvancing the delivery and aspiration catheter of FIGS. 1-3 to a pointproximal to the thromboembolism according to a method for using thesystem of FIG. 1.

FIG. 18 is a partial section side view illustrating deployment of thethromboembolic receiver of FIGS. 1-3.

FIG. 19 is a partial section side view illustrating advancement of thedelivery and aspiration catheter of FIGS. 1-3 distally such that thethromboembolic receiver of FIGS. 1-3 engages (fully or partially) thethromboembolism.

FIGS. 20 and 21 are partial section side views illustrating movement ofthe thromboembolic receiver of FIGS. 1-3 into the guide and occlusioncatheter so as to remove the thromboembolism.

FIG. 22 is a partial section side view illustrating use of thethromboembolic separator of FIGS. 1 and 9-11C to engage the distal endof the thromboembolism.

FIG. 23 is a partial section side view illustrating use of thethromboembolic separator of FIGS. 1 and 9-11C to fragmentize and/orsoften the thromboembolism and/or aid aspiration.

FIG. 24 is a partial section view illustrating independent use of thethromboembolic separator of FIGS. 1 and 9-11C to fragmentize and/orsoften the thromboembolism and/or aid aspiration.

FIGS. 25 and 26 are partial section side views illustrating advancementof the thromboembolic receiver of FIGS. 4-6 distally such that itenvelopes the thromboembolism.

FIGS. 27 and 28 are a partial section side views illustrating withdrawalof the thromboembolic receiver of FIGS. 4-6 and the delivery andaspiration catheter into the guide and occlusion catheter so as toremove the thromboembolism.

FIG. 29 is a perspective view of yet another alternate thromboembolicseparator, which combines some of the features of a receiver and aseparator in order to function as an improved separator equipped with aseries of engagement cages, where the engagement cages are framed byuprights and apexes, and each engagement cage is defined by a pair ofrib apexes that is adjoined to an adjacent pair of rib apexes.

FIG. 30 is an alternate perspective view of the thromboembolic separatorof FIG. 29. The thromboembolic separator of FIG. 29 is rotated slightlyto reveal the perspective view of FIG. 30.

FIG. 31 is a plan (rolled out) view of the cut pattern of thethromboembolic separator of FIGS. 29 and 30. Although the separator ispreferably a generally tubular structure, FIG. 31 illustrates it opened,flattened, and with the ribs forming the engagement cages of FIGS. 29and 30 detached from one another, so that the features are more easilyviewed.

FIG. 32 is a side view of the thromboembolic separator of FIGS. 29 and30 disposed within a curved portion of a vessel, where the vessel isshown in cross section.

FIG. 33 is a perspective view of an alternate thromboembolic separator.The separator of FIG. 33 has the cut pattern illustrated in FIG. 31, butit is finished in a manner that is slightly different than the methodused to finish the separator of FIGS. 29 and 30.

FIG. 34 is a plan view of an alternate cut pattern for a thromboembolicseparator. Although a resulting thromboembolic separator formed from thepattern of FIG. 34 is preferably a generally tubular structure, FIG. 34illustrates it opened and flattened, and with the ribs forming theengagement cages detached, so that the features are more easily viewed.

FIG. 35 is a perspective view of yet another alternative embodiment of athromboembolic separator according to the invention.

FIG. 36 is an alternate perspective view of the thromboembolic separatorof FIG. 35. The thromboembolic separator of FIG. 35 is rotated slightlyto reveal the perspective view of FIG. 36.

FIG. 37 is a plan view or rolled out of the cut pattern of thethromboembolic separator of FIGS. 35 and 36. Although the separator ispreferably a generally abstract tubular structure, FIG. 37 illustratesit opened and flattened, and with the ribs forming the engagement cagesof FIGS. 35 and 36 unattached, so that the features are more easilyviewed.

DETAILED DESCRIPTION OF THE INVENTION

Illustrative embodiments of the invention are described below. In theinterest of clarity, not all features of an actual implementation aredescribed in this specification. It will of course be appreciated thatin the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure. The thromboembolic removal system disclosed hereinboasts a variety of inventive features and components that warrantpatent protection, both individually and in combination.

System Features

FIG. 1 illustrates an exemplary embodiment of a thrombolic removalsystem 10. The thromboembolic removal system 10 includes a guide andocclusion catheter 12, a delivery and aspiration catheter 14, athromboembolic disrupter or separator 16, and an aspiration pump 18. Aswill be described in greater detail below, the thromboembolic removalsystem 10 advantageously provides the ability to restore patency to andremove a thromboembolism from a cerebral artery within a patient whileovercoming the drawbacks and limitations of the prior art.

The guide and occlusion catheter 12 includes a tubular catheter member20 having a main lumen 22 extending between a proximal end 24 and adistal end 26. The catheter member 20 may be constructed from any numberof compositions having suitable biocompatibility and strengthcharacteristics, and may be dimensioned in any number of suitable sizesand lengths depending upon the entry point into the vasculature, thelocation of the thromboembolism, variances in patient anatomy, and anyextenuating circumstances. In an exemplary embodiment, the cathetermember 20 may be constructed from nylon with embedded stainless steelbraid and dimensioned having a length ranging from 70 cm to 110 cm and adiameter ranging from 5 French (0.065 inch) to 9 French (0.117 inch). Aballoon occlusion member 28 is disposed at or near the distal end 26. Toselectively inflate the occlusion member 28, an inflation port 30 isprovided in fluid communication with the occlusion member 28 via atleast one lumen (not shown) disposed within the wall of the tubularcatheter member 20. A seal 32 is provided for passing the delivery andaspiration catheter 14 through the main lumen 22 of the guide andocclusion catheter 12 in leak-free, hemostatic fashion.

The delivery and aspiration catheter 14 includes a tubular catheterelement 34 having a main lumen 36 extending between a distal end 38 anda proximal end 40. The catheter member 34 may be constructed from anynumber of compositions having suitable biocompatibility and strengthcharacteristics, and may be dimensioned in any number of suitable sizesand lengths depending upon the entry point into the vasculature, thelocation of the thromboembolism, variances in patient anatomy, and anyextenuating circumstances. In an exemplary embodiment, the cathetermember 34 may be constructed from pebax with embedded stainless steelbraid and dimensioned having a length ranging from 130 cm to 170 cm anda diameter ranging from 2.5 French (0.032 inch) to 5 French (0.065inch).

The delivery and aspiration catheter 14 also includes a hub assembly 42coupled to the proximal end 40 for the purpose of coupling the lumen 36to the aspiration pump 18. The hub assembly 42 also includes a seal 44for allowing the passage of the thromboembolic separator 16 (as well asany pushing devices to deploy a receiver element 46, as will bediscussed below) through the lumen 36 in leak-free, hemostatic fashion.The lumen is preferably coated with PTFE or another of the varioussuitable lubricious materials known in the art.

As best viewed with reference to FIGS. 2-3, the thromboembolic receiverelement 46 is capable of being restrained in a withdrawn or undeployedstate within the lumen 36 (FIG. 2) and selectively pushed out and/orunsheathed from the distal end 38 into a deployed state (FIG. 3). Thethromboembolic receiver 46 may be constructed from any number ofcompositions having suitable biocompatibility and strengthcharacteristics, and may be dimensioned in any number of suitable sizesand lengths depending upon the location of the thromboembolism,variances in patient anatomy, and the size and shape of thethromboembolism. As best viewed in FIGS. 3 and 5, the thromboembolicreceiver 46 is formed from a plurality of strut members 47, which uponbeing deployed, create a multitude of generally diamond-shaped openings49 along the periphery of the thromboembolic receiver 46. According toone embodiment, as shown in FIGS. 18-23, the resulting points at thedistal region of the thromboembolic receiver 26 are equipped with blunttip features 51 to facilitate passage of the thromboembolic receiver 46through the cerebral artery without snagging or becoming otherwise stuckon the arterial walls or branch vessels leading into the cerebralartery.

A pusher element 48 may be provided within the catheter element 34 foruse in advancing or pushing the receiver element 46 from within thelumen 36 to assume a fully or partially deployed state. By way ofexample only, the pusher element 48 comprises an elongate member 50 ofsuitable construction (e.g. wire or wire-wound) having a distal abutment52 dimensioned to contact proximal terminal(s) 54 forming part of (orcoupled to) the receiver element 46. Although not shown, it will beappreciated that the pusher element 48 may comprise any number ofsuitable devices for pushing the receiver element 46 for deployment,including but not limited to a catheter having a distal end dimensionedto contact the proximal terminal(s) 54 of the receiver element 46. Inone embodiment, such a pusher-catheter may have an internally disposedlumen dimensioned to receive and/or pass the thromboembolic separator16.

FIG. 4A illustrates a thromboembolic receiver 146 of an alternateembodiment. The thromboembolic receiver 146 may be constructed from anynumber of compositions having suitable biocompatibility and strengthcharacteristics, and may be dimensioned in any number of suitable sizesand lengths depending upon the location of the thromboembolism,variances in patient anatomy, and the size and shape of thethromboembolism. In a preferred embodiment, the thromboembolic receiver146 is constructed from Nitinol with “shape memory” or superelasticcharacteristics. In this fashion, the thromboembolic receiver 146 iscapable of being retained in a constrained form or shape prior todeployment. The receiver may be formed by laser cutting features into alength of Nitinol tubing, and then chemically etching and shape-settingthe material one or more times using methods known to those skilled inthe art.

Referring to FIG. 4A, receiver 146 is mounted to an elongate member 151preferably proportioned to extend through lumen 36 (FIG. 1) of thedelivery and aspiration catheter 14. Strut members or “legs” 162 extendbetween receiver 146 and elongate member 151 using bonding, shrinktubing, or other known methods. In a preferred embodiment, member 151 isan elongate rod, catheter, wire or other elongate member. In thisembodiment, the thromboembolic receiver 146 is proportioned so that itmay be constrained in a compressed position within the delivery andaspiration catheter 14 (in a manner similar to that shown in FIGS. 1-3).Alternatively, the elongate member 151 may be the delivery andaspiration catheter 14, in which case the receiver 146 and delivery andaspiration catheter 14 are proportioned to extend through the guide andocclusion catheter 12.

In either event, the thromboembolic receiver 146 may be automaticallydeployed—due to the shape memory or superelastic characteristics ofNitinol—by simply advancing the thromboembolic receiver 146 out of theelement constraining it in the undeployed state (e.g. the guide andocclusion catheter 12 or the delivery and aspiration catheter 14). Oncedeployed, the thromboembolic receiver 146 may be employed to retrieve athromboembolism. The dimensions of the receiver 146 are preferablyselected such that when it is in an expanded condition at bodytemperature, the exterior surface of the distal portion of the receivercontacts the surround walls of the blood vessel. In one embodimentsuitable for more intracranial vessels, the receiver may expand to amaximum outer diameter of approximately 2-6 mm, and more preferably 2-5mm. For other applications such as procedures within the common carotidartery, a maximum outer diameter in the range of approximately 6-9 mmmay be suitable.

The thromboembolic receiver 146 may be formed having any variety ofsuitable geometries and features without departing from the scope of thepresent invention. According to one embodiment shown in FIGS. 4A and 5,the thromboembolic receiver 146 is formed from a plurality of strutmembers, which upon being deployed, create a multitude of generallyrectangular openings 149 (best viewed in FIG. 5) along the periphery ofthe thromboembolic receiver 146. This is accomplished, by way ofexample, by providing a plurality of longitudinal strut members or“standards” 150 (which are generally parallel to the longitudinal axisof the delivery and aspiration catheter 14), and a plurality oftransverse strut members 152 (which extend generally perpendicularlybetween the adjacent standards). In a preferred embodiment, the strutmembers collectively define a generally cylindrical distal portionhaving a central lumen 147 as shown in FIG. 4B.

The transverse strut members 152 may include any number of curves orundulations, such as curves 153 a shown near the points of intersectionbetween the transverse strut members 152 and the standards 150, as wellas the curves 153 b midway between the points of intersection as shownin FIG. 5. Such curves or undulations help allow the thromboembolicreceiver 146 to fold into a compressed or constrained state, which isrequired in order to dispose the thromboembolic receiver 146 within thedelivery and aspiration catheter 14 or within the guide and occlusioncatheter 12.

The transverse strut members 152 form, in a preferred embodiment, aproximal cuff 154 located closest to the delivery and aspirationcatheter 14, a distal cuff 156 located at the distal or open end of thethromboembolic receiver 146, and a middle cuff 158 located at some pointbetween the proximal and distal cuffs. Each cuff (proximal 154, middle158, and distal 156) is a circumferential ring designed to enhance thestructural support and stability of the thromboembolic receiver 146, aswell as to aid in maintaining the thromboembolic receiver 146 in adesired shape upon deployment (for improved apposition to the vesselwall to optimize the thromboembolic retrieval).

The structural support provided by the cuffs 154-158 may be augmented byproviding one or more stabilizing strut members 160 within one or moreof the generally rectangular openings 149. According to one embodiment,these stabilizing strut members 160 may take the form of a “V” extendingfrom either the proximal end or distal end of a given generallyrectangular opening 149 within the thromboembolic receiver 146. In apreferred embodiment, such “V” shaped stabilizing strut members 160 areprovided within the proximal and distal set of generally rectangularopenings 149 within the thromboembolic receiver 146. This advantageouslyadds to the structural stability of the proximal and distal regions ofthe thromboembolic receiver 146. Regardless of their specific shape, thestabilizing strut members 160 preferably include folding regions orapexes 169 that allow them to fold at the apexes 169 (see arrows A inFIG. 5) when the receiver is compressed into the collapsed position.Additionally, the receiver is preferably constructed so as to permit thestrut members 160 to fold in the region where they intersect with otherelements forming the receiver (e.g. in the FIG. 5 embodiment, the regionof intersection between strut members 160 and standards 150).

While structural stability of the thromboembolic receiver 146 is adesired goal, it is also desired to have certain aspects of flexibility.According to one embodiment, relative flexibility is provided at thejunction between the thromboembolic receiver 146 and the elongate member151 (or the distal end of the delivery and aspiration catheter 14). Thisis accomplished, by way of example only, by providing the plurality ofconnector strut members or “legs”162 extending between the proximal cuffand the elongate member 151 to include (as best viewed in FIG. 5) a flexregion 164 near the distal end of the elongate member 151. The flexregions 164 may be formed into any shape that will add flexibility tothe strut members 162 without comprising the user's ability to transmitaxial forces along the length of the strut members 162. In an alternateembodiment shown in FIG. 6, the flex regions 164 a may comprise aplurality of meandering “S” shaped struts 166 a at the proximal ends ofthe connector struts 162. According to another embodiment, a flex regionor spring region 168 (FIG. 5) (which may comprise one of more “S” shapedcurves or other shapes designed to provide flexibility while maintainingadequate column strength) may be provided at the junction betweenadjacent longitudinal strut members or standards 150. In both instances,such flex regions 164, 168 are advantageous in that they allow thethromboembolic receiver 146 to better track and follow tortuous vesselswithout sacrificing needed column strength.

According to a further embodiment, the thromboembolic receiver 146 mayalso include a variety of features to augment engagement between thethromboembolic receiver 146 and the thromboembolism. This may beaccomplished, by way of example only, by providing a plurality ofengagement elements 170 on the thromboembolic receiver. As best viewedin FIGS. 4A, 4B and 5, the engagement elements 170 may, according to oneembodiment, take the form of a “V” shaped structure coupled at or nearthe distal end of the thromboembolic receiver 146 and extending betweenadjacent standards 150. The engagement elements preferably angle intothe lumen 147 of the thromboembolic receiver (see FIGS. 4B and 4C) so asto permit engagement of a thromboembolism captured within the lumen. Anynumber of engagement elements 170 may be employed without departing fromthe scope of the present invention. In one embodiment, three (3)separate engagement elements 170 may be employed, each being disposedone hundred and twenty (120) degrees from one another along theperiphery of the thromboembolic receiver 146. In a preferred embodiment,the engagement elements 170 take the form of a plurality of thestabilizing strut members 160 as shown in FIGS. 4A and 5.

The engagement elements 170 may be deployed automatically when thethromboembolic receiver 146 is deployed (as shown in FIG. 4-5). Inaccordance with another aspect of the invention shown in FIG. 7, theengagement elements 170 a may also be selectively deployed at any pointfollowing the deployment of the thromboembolic receiver 146 a. Accordingto the FIG. 7 embodiment, the selective deployment of the engagementelements 170 a is accomplished by passing one or more elongate elements172 through the thromboembolic receiver 146 a such that the engagementelements 170 a are prevented from extending medially into the lumen ofthe thromboembolic receiver 146. When deployment is desired, a user needonly pull the elongate elements 172 in a proximal direction (towards theuser) until the engagement elements 170 a are set free from theconstraint of the elongate elements 172. When this occurs, the “shapememory” or superelastic nature of the engagement elements 170 a willcause them to assume their natural state, extending medially into thelumen of the thromboembolic receiver 146 a. In this fashion, theengagement elements 170 a will engage the thromboembolism and thus aidor enhance the ability of the thromboembolic receiver 146 a to remove athromboembolism.

The thromboembolic receiver may be provided with features that allow asurgeon to retract the receiver back into the delivery and aspirationcatheter after the receiver has been partially or fully deployed into ablood vessel. This might be necessary if, perhaps, the surgeon receivesangiographic or tactile feedback indicating that a separator would be apreferred tool for removal of a particular embolism, or that a receiverof a different size would be more suitable for a particular procedure.

FIG. 8A illustrates one example of an embodiment of a thromboembolicreceiver 146 b that is similar to the receiver 146 of FIG. 4, but thatincludes the features that facilitate reloading of the receiver into thedelivery and aspiration catheter 14. As shown, receiver 146 b of theFIG. 8A embodiment includes a single, distal, cuff 152 b and a pluralityof longitudinal strut members 150 b extending proximally from the cuff152 b.

Structural support members 160 b are arranged in a distal row 171 aadjacent to the cuff 152 b, and a more proximal row 171 b as shown inFIG. 8B. As with the FIG. 4 embodiment, a plurality of the structuralsupport members 160 b in the distal row are inwardly biased into thecentral lumen 147 b of the receiver 146 b so as to function asengagement members 170 b for engaging a thromboembolism.

Three types of stabilizing strut members extend towards the proximal endof the receiver 146 b. First, strut members 162 b extend distally fromthe apexes of those of the structural support members 160 b in thedistal row 171 a that do not function as engagement members. These strutmembers 162 b are coupled at an intermediate point to the apexes oflongitudinally aligned support members 160 b in the proximal row.Second, strut members 162 c form the proximal extensions of thelongitudinal strut members 150 b and include eyelets 163 at theirproximal ends. Third, strut members 162 d extend from the apexes ofthose of the structure support members 160 b in the proximal row thatare longitudinally aligned with the engagement members 170 b.Flexibility may be added to the receiver 146 b may constructing some orall of the strut members to include flex regions of the type describedin connection with earlier embodiments (see, e.g. flex regions 168 ofFIG. 5).

Referring to FIG. 8C, the receiver 146 b includes a pusher or elongatemember 151 b that includes a lumen 165 at its distal end. Duringassembly of the receiver 146 b, the proximal ends of strut members 162 band 162 d are positioned within the lumen 165 as shown and are allowedto slide freely within the lumen 165. The proximal ends of strut members162 c are bonded to the exterior surface of the elongate member 151 busing heat shrink tubing 167 or other suitable material. The eyelets 163facilitate bonding by allowing the bonding material to flow into theopenings of the eyelets, thereby exposing a larger portion of each strutmember 162 c to the bonding material. If desired, the strut members 162b and 162 d may be somewhat longer than the strut members 162 c at theproximal end of the receiver, to allow them to be easily identified forinsertion into the lumen 165 during assembly.

If it should be necessary to withdraw the receiver 146 b back into thedelivery and aspiration catheter 14 from a fully or partially deployedstate, the elongate member 151 b is withdrawn in a proximal directionrelative to the catheter as shown in FIG. 8C. As the receiver 146 bmoves into the catheter 14, the receiver begins to fold at the apexes ofthe structural support members 162 b and 162 d in a proximal direction.Folding is more easily accomplished than with the receiver 146 of FIG. 4due to the fact that certain of the structural support members 160 b areinterconnected at their apexes by strut members 162 b. Thus, the foldingof one member 160 b in the proximal row 171 b will facilitate thefolding of a corresponding member 160 b in the distal row 171 a. Thestrut members 162 b and 162 d are allowed to slide freely within thelumen 165 of the elongate member 151 b so that they will not resistfolding of the members 160 b during withdrawal of the receiver 146 binto the catheter 14.

A first embodiment of a thromboembolic separator is shown in FIG. 9. Thethromboembolic separator 16 of the first embodiment includes anelongated element 56 having a proximal end 58 and a distal end 60. Theelongated element 56 may be constructed from any number of compositionshaving suitable biocompatibility and strength characteristics, and maybe dimensioned in any number of suitable sizes and lengths dependingupon the entry point in vasculature, the location of thethromboembolism, variances in patient anatomy, and any extenuatingcircumstances. In an exemplary embodiment, the elongated element 56 maybe constructed from stainless steel and/or Nitinol and dimensionedhaving a length ranging from 150 cm to 200 cm and a diameter rangingfrom 0.010 inch to 0.021 inch. A lubricious surface (e.g., a PTFEcoating, hydrophilic coating, or other suitable coatings) may be appliedto all or a portion of the elongate element 56 to facilitate movement ofthe element within the lumen of the delivery/aspiration catheter 14and/or within the vasculature.

If desired, the elongate element 56 may take the form of a guide wire ofthe type used in various vascular applications. The elongate element maythus optionally include a coiled distal section 57 (FIG. 11B) havingsufficient flexibility to prevent trauma to vascular tissues duringadvancement of the guidewire. In an exemplary embodiment, coiled distalsection 57 may have a length in the range of approximately 27-33 cm. Thecoil is preferably positioned around an inner mandrel or core (notshown) of a type commonly found in coiled guidewires.

The “working end” of the separator 16 includes a generally blunt tipelement 62 attached or forming part of the distal end 60 of theelongated element 56, and a separator element 64 attached or formingpart of the elongated element 56. The tip element 62 is preferablydimensioned to pass through or against a thromboembolism so as to softenor fragment the thromboembolism for removal. The blunt nature of the tipelement 62 is advantageously atraumatic such that it will not causedamage to the interior of the vasculature during use. The separator 16also assists in removing any clogs or flow restrictions that may developwithin the lumen 36 due to the passage of thromboembolic materialtherethrough during aspiration.

In one embodiment, as best shown in FIG. 11A, the separator element 64may take the form of a basket that is generally conical in shape, withan opening 66 facing proximally along the elongated element 56. Theseparator basket 64 is dimensioned to assist in the thromboembolicfragmentation process, as well as to receive such thromboembolicfragments to aid in their removal. In one embodiment, the separatorbasket 64 is provided having a web 68 and one or more support members70. The support members 70 are dimensioned to bias the web 68 into thegenerally open position shown and, if desired, to allow the web 68 toassume a generally closed position (not shown, but generally flushagainst the elongated element 56) as the separator 16 is passed throughdelivery and aspiration catheter-style pusher as described above, and/orthe thromboembolism itself.

An alternative embodiment of a separator 16 aa is shown in FIGS. 11B and11C, in which like reference numerals are used to identify featuressimilar to those shown in FIGS. 9, 10 and 11A. Separator 16 a differsfrom separator 16 of FIGS. 9, 10 and 11A primarily in the features ofthe separator element 64 a. Referring to FIG. 11B, separator element 64a is a conical member formed of a polymeric material such aspolyurethane or Pebax® polyether block amides, to name a few. Theseparator element 64 a is preferably a solid member, with a surface 65facing in the proximal direction, and with the taper of the elementoriented in a distal direction. Surface 65 may be contoured in a varietyof ways. For example, surface 65 may be slightly concave as shown inFIG. 11B, substantially planar as shown in FIG. 11C, or slightly convexas shown in FIG. 11D.

The separator element 64 a is positioned on the coiled distal section 57of the elongate element 56. The pitch of a portion of the coiled section57 may be decreased in certain regions of the coiled distal section 57.Opening the spacing in the coil in this manner can facilitate adhesionbetween the polymeric material of the separator element and the coilmaterial during the molding process. The spacing between the separatorelement 64 a and the distal end 60 of the elongate element 56 ispreferably long enough to allow the distal-most portion of the elongateelement sufficient flexibility to move atraumatically through thevasculature, but short enough to prevent folding of the distal-mostportion during advancement of the elongate element 56. In an exemplaryembodiment, the distal end of separator element 64 a may be positionedapproximately 3-9 mm from the distal end 60. It should be noted that themandrel or core (not shown) within the coiled section 57 of the elongateelement 56 might have a tapered diameter selected to enhance theflexibility of the coiled section.

A handle member 72 (FIG. 9) is provided at the proximal end 58 of theseparator to provide a purchase point for a user to advance and/ormanipulate the atraumatic tip element 62 and separator 64/64 a. In oneembodiment, the handle member 72 may be coupled to the elongated element56 in any suitable fashion, including, but not limited to providing agenerally rigid extension (not shown) disposed within the elongatedelement 56 for the purpose of coupling the two components together. Thiscoupling may be augmented or strengthened through the use of any numberof adhesives or fusing techniques.

The separator 16 may be provided in a variety of different permutationswithout departing from the scope of the present invention. For example,in addition to the “self deployable” embodiment described above, theseparator basket 64 of FIG. 11A may be selectively deployed, such as byequipping the separator basket 64 with a mechanism to selectively biasor open the support members 70 from an initial position lying generallyflush against the elongated element 56 to a generally radially expandedposition (shown with arrows in FIG. 11A).

It will be appreciated that the guide and occlusion catheter 12, thedelivery and aspiration catheter 14, the thromboembolic separator 16and/or the thromboembolic receiver 46 may be provided with any number offeatures to facilitate the visualization of these elements duringintroduction and usage, including but not limited to having the distalregions equipped with radiopaque markers for improved radiographicimaging.

As discussed previously in connection with FIG. 1, the variouscomponents described herein may be provided as part of the system 10 forremoving thromboembolic material. The thromboembolic removal system 10may include a guide and occlusion catheter 12, a delivery and aspirationcatheter 14, a thromboembolic separator 16/16 a, a thromboembolicreceiver (e.g. receiver 46 or 146), and an aspiration pump 18, as wellas guidewires and/or other tools appropriate for the procedure. In oneembodiment, multiple receivers 46/146 may be provided, allowing thesurgeon to sequentially retrieve several thromboembolisms during thecourse of a procedure. For simplicity, each separate receiver may beprovided with a separate delivery and aspiration catheter. The system 10may additionally be provided with instructions for use setting forth anyof the various methods of use described herein, or equivalents thereof.

System Use

Methods of using the thromboembolic removal system 10 will now bedescribed with reference to FIGS. 12-28. As shown generally in FIGS.12-13, in a first exemplary method the thromboembolic removal system 10is introduced into the patient's vasculature, such as via the Seldingertechnique. FIG. 14 illustrates the first step of this process, whichinvolves advancing a guide wire 104 to a point proximal to athromboembolism 100. The guide wire 104 may comprise any number ofcommercially available guide wires, the operation of which is well knownin the art. However, in one method, the elongate member 56 (FIG. 11B) ofthe separator 16 functions as the guidewire 104.

FIG. 15 illustrates a second step, which involves advancing the guideand occlusion catheter 12 over the guide wire 104 to a point proximal tothe thromboembolism. The next step, shown in FIG. 16, preferablyinvolves inflating the balloon occlusion member 28 so as to arrest theblood flow within the cerebral artery 102 containing the thromboembolism100. As shown in FIG. 17, the delivery and aspiration catheter 14 isthen advanced through the guide and occlusion catheter 12 such that thedistal end 38 of the delivery and aspiration catheter 14 is positionedat a point proximal to the thromboembolism 100. This may be facilitatedby advancing the delivery and aspiration catheter 14 over the guide wire(not shown but well known in the art) extending through the guide andocclusion catheter 12.

At this point, as shown in FIG. 18, the thromboembolic receiver 46 isdeployed from the distal end 38 of the delivery and aspiration catheter14. In one embodiment, the balloon occlusion 28 may be inflated at thispoint (as opposed to inflating it before the delivery and aspirationcatheter 14 is advanced, as shown in FIG. 16). The delivery andaspiration catheter 14 is then advanced distally—as shown in FIG.19—such that the thromboembolic receiver 46 engages and/or envelops(partially or fully) the thromboembolism 100. At this point, as shown inFIGS. 20 and 21, the delivery and aspiration catheter 14 may bewithdrawn into the guide and occlusion catheter 12 to remove thethromboembolism 12 from the patient.

To augment the ability to remove the thromboembolism 100, or in theinstance the thromboembolic receiver 46 does not initially engage thethromboembolism 100, the aspiration pump 18 may be activated toestablish negative pressure within the delivery and aspiration catheter14. In this fashion, negative pressure will be created within thecerebral artery 102 and exerted upon the thromboembolism 100. As notedabove, the separator 16 (or the separator 16 a of FIGS. 11B-D) may beemployed during this process (e.g. advancing and retracting it withinthe lumen 36 of the delivery and aspiration catheter 14) to remove anyclogs or flow restrictions due to the passage of thromboembolic materialthrough the lumen 36. The negative pressure will serve to draw thethromboembolism 10 into (partially or fully) the thromboembolic receiver46. The delivery and aspiration catheter 14 may then be withdrawn intothe guide and occlusion catheter 12 to remove the thromboembolism 100from the patient.

To further augment the ability to remove the thromboembolism 100, or inthe instance the aspiration pump 18 does not adequately draw all or mostof the thromboembolism into the receiver 46, the thromboembolicseparator 16/16 a may be advanced into contact with a portion of thethromboembolism, or completely through the thromboembolism 100 as shownin FIG. 22, and employed to bias or engage the distal end of thethromboembolism 100. This will increase the surface area of engagementwith the thromboembolism 100, which will advantageously allow it to bewithdrawn into the guide and occlusion catheter 12 such as bywithdrawing the separator 16/16 a and delivery and aspiration catheter14 simultaneously into the guide and occlusion catheter 12.

As shown in FIG. 23, the separator 16/16 a may also be selectivelyadvanced and retracted through the thromboembolism 100 (or thatremaining outside the receiver 46). This will serve to break up orotherwise soften the thromboembolism 100. Advancing and retracting theseparator 16/16 a also serves to remove any clogs or flow restrictionswithin the lumen of the delivery and aspiration catheter 14 during theaspiration due to the passage of thromboembolic material through thelumen 36 of the delivery and aspiration catheter 14. In either event,the aspiration pump 18 will draw or bias the thromboembolic fragments106 or the softened thromboembolism 100 into the thromboembolic receiver46 and/or into catheter 14. The delivery and aspiration catheter 14 maythen be withdrawn such that the thromboembolic receiver 46 is drawn intothe guide and occlusion catheter 12 to remove the thromboembolism 100from the patient.

Selective advancement of the separator element 64 through thethromboembolism and retraction of the separator element into thedelivery and aspiration catheter 14, preferably in combination withaspiration, can additionally be used to carry small “bites” of thethromboembolic material, displacing some material and thus forming achannel in the material as it moves distally. Once the separator elementis positioned further into, or distally of, the thromboembolism, some ofthe displaced material may flow back into this channel. Subsequentretraction of the separator element 64 through the material (e.g.through the re-filled channel) will then draw some of the material intothe catheter 14. To facilitate this procedure, the separator element 64and the catheter 14 are preferably provided with fairly tight tolerancesbetween the diameter of the catheter lumen 36 and the greatest diameterof the separator element 64. For example, in one exemplary embodiment,the outer diameter of separator element 64 and the diameter of lumen 36may differ by approximately 0.003-0.008 inches.

An alternative method will next be described in which the receiver anddisrupter are preferably used independently of one another, althoughcombined use such as that described in connection with the firstexemplary method might also be used. This method will be described asperformed using the thromboembolic receiver 146 and the separator 16 a,however it should be appreciated that other embodiments of thesecomponents may alternatively be used in the disclosed method.

According to the alternative method, an initial determination is madeconcerning whether use of receiver 146 or separator 16 a will first beemployed. This determination may be made at random, although in apreferred method the surgeon selects the appropriate tool based on adetermination of the likely nature of the thromboembolic material thatis to be removed. In particular, the surgeon will assess the patient todetermine whether the material is likely to be hard or soft/gelatinous.This assessment might include an evaluation of one or more factors suchas the response of the tip of the guidewire or separator when it isbrought in contact with thromboembolism, the location of thethromboembolic material, patient symptoms, and/or the manner in whichthe stroke caused by the thromboembolism is manifesting itself.

As discussed in connection with the first exemplary method, the guideand occlusion catheter 12 is introduced into the patient's vasculature,and the occlusion balloon 28 is inflated to arrest the flow of bloodwithin the vessel (see, for example, FIGS. 14-16).

The delivery and aspiration catheter 14 is passed through the guide andocclusion catheter 12 and positioned with its distal end at a locationproximal to the thromboembolism 100. If the surgeon elects to use theseparator 16 a prior to using the receiver 146, or if the assessmentresults in a determination that the thromboembolic material is likely tobe somewhat soft or gelatinous, the aspiration pump 18 is activated toestablish negative pressure within the delivery and aspiration catheter14, and thus to exert negative pressure exerted upon the thromboembolism100 to draw embolic material into the catheter 14.

The separator 16 a is deployed from the distal end of the delivery andaspiration catheter 14 and moved into contact with the thromboembolicmaterial 100 as shown in FIG. 24. The separator may be advanced andretracted multiple times if desired. When advanced and retracted asshown, the separator can facilitate aspiration of the thromboembolicmaterial into the catheter 14 in one of a variety of ways. First,movement of the separator into contact with the thromboembolism canloosen, separate, or soften pieces of thromboembolic material, such thatpieces of the thromboembolism can be aspirated into the catheter.Second, advancing and retracting the separator 16 a serves to remove anyclogs or flow restrictions within the lumen 36 of the delivery andaspiration catheter 14 that might be caused by the passage ofthromboembolic material through the lumen 36. Additionally, duringretraction of the disrupter 16 a, its proximal surface 35 may push orplunge loosened material towards and/or into the distal end of thecatheter 14 for subsequent aspiration out of the body.

If use of the disrupter 16 a as just described reveals that the vesselincludes a hard mass of thromboembolic material incapable of aspirationwithout further intervention, the disrupter 16 a is preferably withdrawnfrom the catheter 14 and a thromboembolic receiver 146 is passed throughthe delivery and aspiration catheter 14 and deployed within the bloodvessel. If the system is provided with multiple sizes of receivers, thesurgeon will select a receiver having an appropriate size for the bloodvessel being treated.

Referring to FIGS. 25-28, once the receiver 146 is deployed, it expandsinto contact with the surrounding walls of the vessel. As the receiver146 is advanced towards the body thromboembolic material 200, the wallsof the receiver 146 slip around the body 200 to engage and/or envelop(partially or fully) the thromboembolism. The engaging elements 170engage the thromboembolism 200, thereby retaining it within thereceiver. If desired, the delivery and aspiration catheter 14 may beadvanced slightly in a distal direction as indicated by arrows in FIG.27, so as to “cinch” the strut members 162 towards one another, thuscausing the receiver 146 to collapse slightly in a radially inwarddirection. Additionally, the aspiration pump 18 (FIG. 1) may beactivated to facilitate retention of the thromboembolism 200 within thereceiver. The delivery and aspiration catheter 14, the receiver 146 andthe thromboembolism 100 are withdrawn into the guide and occlusioncatheter 12 and are withdrawn from the body. If additionalthromboembolic material should remain in the blood vessel, a newdelivery and aspiration catheter 14 may be passed into the blood vessel,and a new receiver may be deployed through the catheter 14 forretrieving the additional body of thromboembolic material.

Naturally, the surgeon may elect to initially deploy the receiver ratherthan the separator, such as if the initial assessment results in adetermination that the thromboembolic material is likely to be hard. Themethod is then carried out utilizing the receiver 146 as described inthe preceding paragraph. If it is later determined that residualthromboembolic material (e.g. soft or gelatinous material) is present inthe vessel, the receiver 146 is preferably removed from the body, andthe separator 16 a is passed through the delivery and aspirationcatheter 14. The aspiration pump 18 is activated and the separator 16 ais manipulated to facilitate aspiration of the soft material in themanner described above.

Referring now to FIGS. 29 and 30, an alternate embodiment of athromboembolic separator 310 is shown. The thromboembolic separator ofFIGS. 29 and 30 combines many of the features of the receivers andseparators discussed above, in order to perform as an improvedseparator. FIG. 29 is a perspective view of thromboembolic separator310. FIG. 30 is also a perspective view of thromboembolic separator 310,but is rotated slightly from the view of FIG. 29 in order to revealcharacteristics that are not visible in FIG. 29. In turn, FIG. 29 can beconsulted for an illustration of features that are slightly obstructedin the view of FIG. 30. Thromboembolic separator 310 may be constructedfrom any number of materials or compositions having suitablebiocompatibility and strength characteristics, and may be dimensioned inany number of suitable sizes and lengths depending upon the location ofthe thromboembolism, variances in patient anatomy, and the size andshape of the thromboembolism. In the embodiment illustrated in FIGS. 29and 30, the outer diameter of separator 310 in its deployed (radiallyexpanded) configuration may range between 4.6 mm and 5.4 mm to be usedin vessels ranging from 3.0 mm and larger; however other devicediameters may be suitable according to the invention. The length ofseparator 310 when deployed may vary between 12 mm and 20 mm, butpreferably is longer than the length of the thromboembolism, and in thisinstance is approximately 17 mm.

Separator 310 is constructed from a nickel-titanium alloy (Nitinol®)with “shape memory” or superelastic characteristics. Accordingly, thethromboembolic separator 310 is capable of being retained in aconstrained form or shape prior to deployment. The separator may beformed by laser cutting features into a length of Nitinol tubing, thenchemically etching and shape-setting the material, and then attachingcut features to one another to construct a finished device. For example,a tube of 3.5 mm outer diameter and 0.0055 inch wall thickness may becut in a predetermined pattern. Examples of suitable patterns areillustrated as flat patterns in FIG. 31, FIG. 34 and FIG. 37 (as thoughthe tube were cut along a longitudinal axis and laid flat). Otherpatterns may also be suitable. Strut widths that define the elements ofseparator 310 may vary between 0.0011 inch and 0.00165 inch. Struts mayhave a broadened region and one or more tapered regions. After thefeatures are cut into the length of tubing, additional steps (which aredescribed in greater detail below) are performed upon the features ofthe cut tube in order to manufacture the finished separator 310.

The elements of thromboembolic separators according to the invention andillustrated in FIGS. 29-37 are defined by strut members cut into thetubing, some of which undergo additional processing in the manufactureof the finished device. A strut member as used herein is a generic termfor a band-like, wire-like, or other elongate element cut out of thetubing in the early steps of manufacture of a separator according to theinvention. Because a separator according to the invention typically hasnumerous strut members having varied configurations, other terms areused in the following description to distinguish among strut members andin order to avoid confusion. Nonetheless, a particular strut member willbe longitudinal or transverse, curved, undulating, straight deflectedinwardly to occupy a lumen of the tubular separator, or the like. Thelength and width of a strut member may differ from that of another strutmember and may perform a different function in the device. An individualstrut member may have either a uniform or a varied width along itslength.

Some strut members are configured to define “uprights” or “standards”.The terms upright or standard are used interchangeably to describe astrut member that extends generally longitudinally (in a directionparallel to a central axis of the tube) along the length of the device.An upright or standard will typically confer axial or columnar strengthupon the device. In addition, uprights are typically more or lessparallel to one another throughout the length of the device. A first setof uprights at the base of the device may be referred to as “legs”. Anupright or standard may be the same width as or wider than other strutmembers that define the device's structure. An embodiment according tothe invention may have any number of uprights, but those described indetail herein typically have between two and four uprights or standards.

While uprights are more or less parallel to one another, some strutmembers extend from the uprights or standards at an angle to theupright. The angle at which a particular strut member is oriented to aparticular upright may vary widely, and the term angle should beunderstood to mean any angle within the full spectrum greater than 0degrees and less than 180 degrees, but will most often be between 15degrees and 75 degrees. The strut members that extend from an upright atan angle to the upright meet other strut members attached to an oppositeupright and also extending at an angle to the opposite upright. The term“apex” is used herein to refer to two strut members that meet at theirdistal end to form a peak or “apex”. An apex may be pointed or rounded,may be attached to an upright, to another apex (so that in effect fourstruts meet at a common apex), or may be free. An apex may be slightly“cupped” in a deployed device. An apex may be disposed along a “wall” ofa separator or, alternatively, may be disposed or deflected to liewithin a central “lumen” of the separator. Further, an apex may includean additional extension therefrom.

An apex that is left free is referred to as an apex, but with an addedindication of the relative location of the apex. For example, a proximalapex is located at the proximal end of the device, and a distal apex islocated at the distal end of the device. A body apex is located alongthe body of the device, and may be numbered consecutively as first bodyapex, second body apex, and so on, from the proximal end of the deviceto the distal end of the device. An apex that is attached at its distalend to an upright may be referred to as a “fork” at its point ofattachment to the upright. And an apex that is formed where the distalend of an upright divides may be described as “Y-like”. An apex that maybe coupled to another apex in the central lumen of the device isreferred to as a “peak”, whether the apex is coupled or remainsunattached in the finished device. An attached pair of peaks, typicallydisposed within the central lumen of the device, is referred to as a“cage”.

Some of the strut members that extend from the uprights at an angle tothe uprights are given the term “rib” and some are given the term “arm”,depending upon what structure the strut member is attached to. A “rib”is typically a strut member that extends from an upright at an angle tothe upright until it meets another rib coming from an opposing uprightto define a “peak”. A peak may also have a “rib extension” extendingtherefrom. A peak and its respective rib extension may define awish-bone like configuration. A peak may be attached to another peak ormay remain unattached in a finished device. Where a peak is coupled to asecond peak, the paired rib peaks are referred to as a “cage”. Ribs,peaks, and rib extensions forming a cage are typically biased into thecentral lumen of the device when they are coupled with a second pair ofribs, peaks and extensions.

An “arm” is also a strut that extends from an upright at an angle to theupright. Arms extend generally in a “Y-like configuration” in a distaldirection from an upright. Distal to the point where arms divide in aY-like fashion, two arms meet again at a subsequent upright. The term“fork” may be used to describe the point at which two arms meet at adistal upright to define an apex. While all of the foregoing terms referto struts and apexes, it is hoped that the additional terms enable aclearer distinction among struts and apexes and a clearer description ofa device according to the invention.

After material is removed from a Nitinol tube according to apredetermined pattern, and following the final steps to constructseparator 310, the structure of separator 310 is a generally skeletaldevice bearing “internal” elements. The body abstracted from the tubehas large voids in its “walls” and loosely defines a central axis 330therethrough. The abstract tube has an outer circumference disposedabout the central axis. The series of internal elements is disposedabout central axis 330. These internal elements are referred to asengagement cages 350, 351, 352 and 353. Separator 310 (FIGS. 29 and 30)includes four such engagement cages 350, 351, 352 and 353, but mayaccording to the invention include a greater or lesser number.Engagement cages 350, 351, 352 and 353, along with other elements of thedevice, engage embolic material in a vessel of a subject during use ofseparator 310, in order that the embolic material may be removed andvessel patency restored.

Engagement cages 350, 351, 352 and 353 are framed first by uprights (orstandards) 320, 321, 322 and 326 respectively. Engagement cage 350 isalso framed by proximal apexes 313, and by two pairs of arms 323.Proximal apexes 313 may cup slightly in the expanded device. Each pairof arms 323 meets to form forks 330 at subsequent uprights 321.Engagement cage 351 is also framed by two pairs of arms 325. Each pairof arms 325 meets to form forks 332 at subsequent uprights 322.Similarly, engagement cage 352 is also framed by two pairs of arms 327,which meet to define forks 334 at subsequent uprights 326. Andengagement cage 353 is framed by distal apexes 357. Similar to proximalapexes 313, distal apexes 357 may cup slightly in an expanded device.

In FIGS. 29 and 30, separator 310 is shown mounted to pusher 315, whichis proportioned to extend through the lumen of a delivery and aspirationcatheter such as the PX400 catheter or other suitable cathetersavailable from Penumbra, Inc. in Alameda, Calif. Other straight lumencatheters having an inner diameter of between 0.025-0.032 inch may besuitable. A suitable pusher catheter may be constructed from Pebax HStubing or comparable material, available from Zeus Medical ofOrangeburg, S.C., though other materials and alternative dimensions maybe suitable according to the invention. A separator according to theinvention may in the alternative be mounted to a delivery wire,depending upon the dimensions and requirements of the delivery catheterused to deliver the separator to the treatment site. A delivery wire maybe of 0.014 inch distal diameter and 0.020 inch proximal diameterstainless steel, Nitinol or other metal, or other suitable dimensionsand materials. If mounted upon a delivery wire, separator 310 may bemounted approximately 5 cm from the distal end of the wire, but otherconfigurations are possible. Separator 310 may advantageously be mountedeccentrically to the pusher or delivery wire. Thromboembolic separator310 is mounted to the distal end of pusher 315 via legs 318.

The separator 310 illustrated in FIGS. 29 and 30 is finished, but manyof its features may be more readily understood by referring to FIG. 31.FIG. 31 illustrates flat (rolled out) pattern 311. Beginning at itsproximal end 312, legs 318 extend distally to form a first set ofuprights 320. Proximal apexes 313 are attached between adjacent uprights320. Base end 314 of separator 310 is thereby defined by legs 318,uprights 320, and proximal apexes 313. Proceeding distally from proximalapexes 313, and ignoring ribs 335 (and engagement cages 350-353 of thedeployed device) for now, the distal end of each upright 320 divides ina Y-like fashion to form a first set of arms 323. Each arm 323 extendsat an angle to uprights 320, or generally diagonally to meet an adjacentarm 323 at fork 330 as each arm 323 joins a subsequent set of uprights321 extending therefrom. This pattern, which can be most easily seen inFIG. 31, repeats until the distal end 359 of separator 310. The body 316of separator 310 is thus defined primarily by successive sets ofuprights 320, 321, 322 and 326, successive sets of arms 323, 325 and327, and forks 330, 332, and 334, where the number of the sets can varyaccording to the invention. Uprights 320, 321, 322 and 326, arms 323,325 and 327, and forks 330, 332 and 334 skeletally frame a series ofengagement cages, which will be described in detail below. Each set ofuprights is oriented around the circumference of separator 31 at roughly90° to its adjacent set of uprights, as most easily seen in FIG. 30.

The distal end 359 of separator 320 is defined by distal apexes 357,which in the deployed separator 310 cup slightly and are oriented atapproximately 90° about the central axis 330, or around the device'scircumference, to proximal apexes 313. Distal apexes 357 roughly framedistal most engagement cage 353. This characteristic is most easily seenin FIG. 30, though other features of separator 310 are obscured when thedevice is viewed from the perspective illustrated in FIG. 30.

Returning now to the proximal end 312 of separator 310, the features ofengagement cages 350 can now be described. Just distal to proximalapexes 313 and extending from each upright 320 is a rib 335. Each rib335 extends at angle to uprights 320 at its point of attachment thereto,or somewhat diagonally, to meet an adjacent rib 335 extending from theopposite direction. In this fashion, each rib 335 meets adjacent rib 335to define a rib peak 317 to form an apex. Further, while otherconfigurations are within the scope of the invention, in separator 310,also extending from each rib peak 317 is rib extension 340. As bestviewed in FIG. 30, ribs 335, rib peak 317 and rib extensions 340together define a wish-bone like configuration. This pattern repeats ateach subsequent set of uprights 321, 322 and 326, defining subsequentsets of ribs 336, 337 and 338 (and apices), and corresponding ribextensions 341, 342, and 343.

During the manufacture of the finished separator 310 illustrated inFIGS. 29 and 30, each rib extension 340, 341 and 343 is biased intocentral lumen 330 until it meets the respective rib extension 340, 341,or 343 approaching from the opposite side of separator 310. Each ribextension 340, 341, 342, and 343 thereby biases each rib 335, 336, 337,and 338 somewhat into central lumen 330. Each rib extension 340, 341,342, and 343 is then mated with its opposing rib extension 340, 341, 342or 343, and attached thereto via a rib extension joiner 345, 346, 348 or349, though other suitable means of attachment are within the scope ofthe invention. Ribs 335, 336, 337 and 338, together with rib extensions340, 341, 342 and 343 thereby form engagement cages 350, 351, 352 and353, disposed within central lumen 330. Separator 310 is shown havingfour such engagement cages 350, 351, 352, and 353 but a device accordingto the invention may have a greater or a lesser number. For example,FIG. 32 illustrates an alternate embodiment, in which only the proximalmost and distal most rib extensions are attached within the centrallumen. The intermediate rib extensions remain unattached, leavingopposing rib peaks generally flush with the “walls” of the device. Theseparator illustrated in FIG. 32 will be discussed in greater detailbelow.

Prior to delivery and deployment of separator 310, separator 310 will becollapsed, crimped down or otherwise reduced to its deliveryconfiguration and restrained therein by a sheath (not shown). Inpreparation for treating a subject, the device within its sheath will beloaded in a delivery catheter. During a procedure performed underfluoroscopic visualization, the delivery catheter is tracked to the siteof the occlusion. The distal end of the catheter is tracked through theocclusion until the distal tip thereof extends beyond the occlusion. Ina slight variation of the methods described above in relation toalternate embodiments, separator 310 is preferably positioned inside athrombus prior to deployment, and advantageously will be of a lengththat is greater than the length of the thrombus.

At this point, the thromboembolic separator 310 is deployed from thedistal end of a delivery and aspiration catheter. The sheath (notpictured) is then withdrawn to allow partial or complete expansion ofthe separator within the vessel. When the sheath is withdrawn to allowexpansion of separator 310, the separator 310 engages a thromboembolismin a vessel. The sheath can then be advanced over thromboembolicseparator 310, which readily collapses back into the sheath. A largeportion or all of the thromboembolism is thereby removed from the vesseland into the catheter. Additional therapeutics, such as pharmacologicagents, may be administered before and/or during deployment if desiredby the physician. In addition, or alternatively, additional mechanicalmeans for removal of thromboembolic material may be deployed while theseparator is in place within the lumen. Further, expansion of theseparator may be increased incrementally during use. And, contrast diemay be injected at any point during deployment of the separator todetermine the extent of restoration of blood flow.

To augment the ability to remove a thromboembolism, in a fashion similarto that described above in connection with other embodiments, anaspiration pump may be activated to establish negative pressure withinthe delivery and aspiration catheter. In this fashion, negative pressurewill be created within the cerebral artery and exerted upon thethromboembolism. To further augment the ability to remove thethromboembolism, or in the instance the aspiration pump does notadequately draw all or most of the thromboembolism into the catheter,the delivery sheath may be advanced over at least a portion of theseparator and into contact with a portion of the thromboembolism, atleast at the proximal end of the separator. This will serve to break up,soften, and/or clear thromboembolic material that is blockingaspiration.

Advancing and retracting the sheath repeatedly also serves to remove anyclogs or flow restrictions within the lumen of the delivery andaspiration catheter during the aspiration due to the passage ofthromboembolic material through the lumen of the delivery and aspirationcatheter. In either event, the aspiration pump will draw or bias thethromboembolic fragments or the softened thromboembolism into theaspiration catheter. The thromboembolic separator and delivery andaspiration catheter may then be withdrawn such that the separator andaspiration catheter remove the thromboembolism from the patient.

As described above, separator 310 is preferably positioned within athromboembolism prior to deployment. In some instances, thethromboembolism is located within a curved vessel, and separator 310will be deployed within a curved vessel. Clear advantages of separator310 are illustrated in FIG. 32, in which separator 310 is shown deployedin a curved vessel model 600. When deployed within a curved tubularvessel, separator 310 resists kinking and collapsing. Further, separator310 may be partially or fully withdrawn into a delivery sheath (notpictured) without kinking or collapsing, repositioned and redeployed.Some portions of separator 310 may expand into contact with thesurrounding walls of the vessel. More specifically, near the proximalend of separator 310, proximal apexes 313 may expand into contact withthe vessel wall, depending upon vessel size and morphology. Near thedistal end of separator 310, distal apexes 357 expand and may or may notcontact with the vessel wall. Some, all, or portions of some or all ofarms 323, 325 and 327, forks 330, 332 and 334, and uprights 320, 321,322 and 326 may also contact the vessel wall. As shown in FIG. 32 withinmodel vessel 600, separator 310 generally conforms to the curvature orbend 605 of the vessel. Engagement cages 350, 351, 352 and 353 mayremain disposed more or less within the central lumen 330, dependingupon the degree of curvature of the vessel, vessel morphology, placementof the length of separator 310 with respect to the curvature 605, andother factors. For example, as illustrated in FIG. 32, portions of someengagement cages 350, 351, 352 and 353 may be disposed in closeproximity to the vessel wall. In any event, the function of theengagement cages 350, 351, 352 and 353 is to engage embolic material inorder to remove it from the vessel. When in actual use by the physician,the separator may be completely resheathed and removed from the vesselwhen desired. Advancement of the sheath and/or retraction of separator310 will cause separator 310 to return to its collapsed configurationwithin the sheath. Embolic material will remain engaged to engagementcages 350, 351, 352 and 353, and will consequently also be removed fromthe vessel, thereby helping to restore blood flow to the vessel.Additional treatment, whether pharmacologic or mechanical, may continueor commence according to the treating practitioners' determination.

FIG. 33 illustrates an embodiment according to the invention that issimilar to that described in FIGS. 29-32, with a few importantdistinctions. A significant distinction of separator 370 from separator310 is that separator 370 includes only two engagement cages 380 and383. The cut pattern for manufacture of separator 370 of FIG. 32 is thesame pattern as that illustrated in FIG. 31. Further, the process ofmanufacturing separator 370 is the same as that used to manufactureseparator 310 except for a few finishing steps. More specifically, inconstructing the finished device from pattern 311, only theproximal-most set of rib extensions 340 and the distal-most set of ribextensions 343 are biased into central lumen 385 and attached to oneanother to form engagement cages 380 and 383. Ribs 336 and 337 remainunattached to adjacent ribs and are part of the outer diameter ofdeployed device 370. And because each set is oriented at roughly 90° toeach subsequent set, unattached ribs 335 have generally the sameorientation as distal apexes 377, and unattached ribs 337 lie generallyoriented with proximal apexes 373. The methods of manufacture andmethods of use of separator 370 are otherwise generally the same asthose methods described above in relation to FIGS. 29-32.

An alternate thromboembolic separator according to the invention may beconstructed using a cut pattern as illustrated in FIG. 34. In thepattern 410 of FIG. 34, proximal end 412 includes legs 418. When in itsfinal form, a thromboembolic separator manufactured from pattern 410will be mounted at its proximal end 412, to a pusher (not pictured) vialegs 418. Legs 418 extend distally from the proximal end 412 to form afirst set of uprights 420. A row of proximal apexes 413 is attached touprights 420. In a finished device, proximal apexes 413 will surround acentral lumen, and further define the base 414 of a separatorconstructed from pattern 410.

Proceeding distally from proximal apexes 413, and ignoring ribs 435,each upright 420 divides in a Y-like fashion and extends substantiallydiagonally to form a first set of arms 423. Each arm 423 extendsdiagonally to join an adjacent arm 423 at a fork 440. From each fork440, a second set of uprights 421 extends. This pattern repeats untilthe distal end of cut pattern 410. The body 416 of pattern 410 is thusdefined primarily by successive sets of uprights 420, 421, 422, andsuccessive sets of arms 423, 425, 427, where the number of both sets canvary according to the invention. Uprights 420, 421, 422, and arms 423,425, 427 will “surround”, or be disposed about, a central axis of afinished device. The distal end of pattern 420 is defined by distalapexes 457, which will also surround a central axis of a finisheddevice.

Returning now to the proximal end 412 of pattern 410, the features ofwishbone elements 450 can now be described. Just distal to proximalapexes 413 and similarly extending from each upright 420 is a rib 435.Each rib 435 extends at an angle to an upright, or somewhat diagonallyto meet an adjacent rib 435 extending from the opposite direction. Inthis fashion, each rib 435 meets adjacent rib 435 to define a rib peak415. Further, extending from each rib peak 415 is rib extension 440.Ribs 435, rib peaks 415 and rib extensions 440 together define wish-bonelike configurations, referred to here as wishbone elements 450. Thispattern repeats at each subsequent set of uprights 421 and 422, definingsubsequent sets of ribs 436, 437 and 438, and corresponding ribextensions 441, 442, and 443.

In order to manufacture of a finished separator from pattern 410, someor all of rib extensions 440, 441 and 443 will be biased into a centrallumen until it meets the respective rib extension 440, 441, or 443approaching from the opposite side. Some or all of rib extensions 440,441, 442, and 443 will then be mated with its opposing rib extension andattached thereto. Some or all of ribs 435, 436, 437 and 438, togetherwith some or all of rib extensions 440, 441, 442 and 443 will therebyform engagement cages disposed within a central lumen of the finisheddevice.

Turning now to yet another alternative embodiment according to theinvention, separator 610 is shown in its deployed configuration in FIGS.35 and 36. The flat pattern 611 cut to manufacture separator 610 isillustrated in FIG. 37. The pattern 611 used to manufacture separator610 is similar to that illustrated in FIG. 31 and described above, withone primary distinction. Pattern 611 includes first body apexes 617 andsecond body apexes 619, in addition to proximal apexes 613 and distalapexes 657. Seen easily in FIG. 36 in a separator 610 illustrated in itsdeployed configuration, proximal apexes 613, first body apexes 617,second body apexes 619 and distal apexes 657 represent successive setsof apexes. And although other suitable configurations are within thescope of the invention, in deployed separator 610, each successive setof apexes is oriented at roughly 90° to the preceding set of apexes.

Separator 610 is otherwise very similar to those described above.Separator 610 when deployed may be between 18-22 mm or other suitablelength, but in this example is approximately 20 mm. Separator 610 ismounted to pusher 615 via legs 618. Separator 610 includes fourengagement cages 650, 651, 652 and 653, but may according to theinvention include a greater or lesser number. Engagement cages 650, 651,652 and 653 engage embolic material in a vessel of a subject during useof separator 610.

Returning to FIG. 37, and beginning at its proximal end 612, legs 618extend distally to form a first set of uprights 620. Proximal apexes 613are attached to uprights 620. (Proximal apexes 613 cup slightly in adeployed separator 610 to partially define a central lumen 630.) Base614 of separator 610 is thus defined by legs 618, uprights 620, andproximal apexes 613. Proceeding distally from proximal apexes 613, andignoring ribs 635 and engagement cages 650-653 for now, the distal endof each upright 620 divides in a Y-like fashion to form a first set ofarms 623. Each arm 623 extends generally diagonally to join an adjacentarm 623 at a fork 630. From fork 630, a second set of uprights 621extends. This pattern repeats until the distal end of pattern 611 orseparator 610. The body 616 of separator 610 is thus defined primarilyby first body apexes 617, second body apexes 619, successive sets ofarms 623, 625 and 627, forks 630, 632 and 634, and successive sets ofuprights 620, 621, 622 and 626, though a greater or lesser number ofsets is within the scope of the invention. In deployed separator 610shown in FIGS. 36 and 37, apexes 613, 617, 619, 657, arms 623, 625 and627, forks 630, 632 and 634, and uprights 620, 621, 622, 626 skeletallyframe the engagement cages and define a central lumen 630. Proximalapexes 613, first body apexes 617, second body apexes 619 and distalapexes 657 in the deployed separator 610 cup slightly, and eachsuccessive set of apexes is oriented at roughly 90° to its preceding setof apexes.

Turning now to the proximal end 612 of separator 610 and pattern 611,the features of engagement cages 650 can now be described. Just distalto proximal apexes 613 and similarly extending from each upright 620 isa rib 635. Each rib 635 extends somewhat diagonally to meet an adjacentrib 635 extending from the opposite direction. In this fashion, each rib635 meets adjacent rib 635 to define a rib peak 615. Further, extendingfrom each rib peak 615 is rib extension 640. As best viewed in FIG. 36,ribs 635, rib peaks 615 and rib extensions 640 together define awish-bone like configuration. This pattern repeats at each subsequentset of uprights 621, 622 and 626, defining subsequent sets of ribs 636,637 and 638, and corresponding rib extensions 641, 642, and 643.

During the manufacture of the finished separator 610 illustrated inFIGS. 36 and 37, each rib extension 640, 641 and 643 is biased intocentral lumen 630 until it meets the respective rib extension 640, 641,or 643 approaching from the opposite side of separator 610. Each ribextension 640, 641, 642, and 643 thereby biases each rib 635, 636, 637,and 638 somewhat into central lumen 630. Each rib extension 640, 641,642, and 643 is then mated with its opposing rib extension 640, 641, 642or 643, and attached thereto via a rib extension joiner 645, 646, 648 or649, though other suitable means of attachment are within the scope ofthe invention. Ribs 635, 636, 637 and 638, together with rib extensions640, 641, 642 and 643 thereby form engagement cages 650, 651, 652 and653, disposed within central lumen 630. Separator 610 is shown havingfour such engagement cages 650, 651, 652, and 653 but a device accordingto the invention may have a greater or a lesser number.

Prior to delivery and deployment of separator 610, separator 610 will becollapsed, crimped down or otherwise reduced to its deliveryconfiguration and restrained therein by a sheath (not shown). Inpreparation for treating a subject, the device within its sheath will beloaded in a delivery catheter. During a procedure performed underfluoroscopic visualization, the delivery catheter is tracked to the siteof the occlusion. The distal end of the catheter is tracked through theocclusion until the distal tip thereof extends beyond the occlusion. Ina slight variation of the methods described in relation to FIGS. 25-28,separator 610 is preferably positioned inside a thrombus prior todeployment, and advantageously will be of a length that is greater thanthe length of the thrombus.

The delivery catheter or sheath (not pictured) is then withdrawn toallow partial or complete expansion of the separator within the vessel.Additional therapeutics, such as pharmacologic agents, may beadministered before and/or during deployment if desired by thephysician. In addition, or alternatively, additional mechanical meansfor removal of thromboembolic material may be deployed while theseparator is in place within the lumen. Further, expansion of theseparator may be increased incrementally during use. And, contrast diemay be injected at any point during deployment of the separator todetermine the extent of restoration of blood flow.

When deployed within a tubular vessel, portions of separator 610 maycontact the surrounding walls of the vessel, depending upon vessel sizeand morphology. More specifically, in addition to contact via the apexesdescribed above, separator 610 may also contact the vessel wall via allor portions of arms 623, 625 and 627 and uprights 620, 621, 622 and 626.Engagement cages 650, 651, 652 and 653 may remain disposed more or lesswithin the central lumen 330, depending upon the degree of curvature ofthe vessel, vessel morphology, placement of the length of separator 610with respect to a curvature within a vessel, and other factors. In anyevent, the function of the engagement cages 650, 651, 652 and 653 is toengage embolic material in order to remove it from the vessel. When inactual use by the physician, the separator may be resheathed and removedfrom the vessel when desired. Retraction of separator 610 will causeseparator 610 to return to its collapsed configuration within the sheath(not pictured). Embolic material will remain engaged to engagement cages650, 651, 652 and 653 and consequently also be removed from the vessel,thereby helping to restore blood flow to the vessel. Additionaltreatment, whether pharmacologic or mechanical, may continue or commenceaccording to the treating practitioners' determination.

While the invention may be modified and alternative forms may be used,specific embodiments of the invention have been illustrated anddescribed in detail. It should be understood, however, that thedescription herein of specific embodiments is not intended to limit theinvention to the particular forms disclosed. The invention and followingclaims are intended to cover all modifications and equivalents fallingwithin the spirit and scope of the invention.

What is claimed is:
 1. A method of manufacture of a system for removalof thromboembolic material from a blood vessel, the method comprisingthe steps of: cutting a plurality of uprights and apexes from a lengthof tubing to form a separator element; adjoining some of the apexes toone another; mounting said separator element to an elongate element. 2.The method according to claim 1, wherein the step of cutting a pluralityof uprights and apexes further comprises cutting said uprights generallyparallel to one another throughout the length of the tubing, and cuttingsaid apexes so that they extend at an angle to the uprights.
 3. Themethod according to claim 1, wherein the step of cutting the apexesfurther comprises cutting the apexes in the wall of the tubing oppositeone another.
 4. The method according to claim 1, wherein the step ofcutting the apexes further comprises cutting apex extensions.
 5. Themethod according to claim 1, wherein the step of cutting the uprightsand apexes further comprises cutting some of the apexes intermediate thelength of the uprights.
 6. The method according to claim 1, wherein thestep of mounting the separator element further comprises mounting theseparator element to the elongate element via one or more of theuprights.
 7. The method according to claim 1, wherein the step ofcutting the apexes comprises cutting a series of pairs of apexes along alongitudinal axis of the tubing, wherein each pair of apexes is orientedat 90° around the axis to each subsequent pair of apexes.
 8. A method ofremoval of thromboembolic material from a blood vessel of a subject, themethod comprising the steps of: introducing into the vessel proximatethe thromboembolic material an elongate member having an expandable andcollapsible separator element disposed at a distal end of the elongatemember, the separator element comprising a plurality of uprights and amultiplicity of apexes extending between said uprights, wherein at leastsome of the uprights and a first group of apexes are disposed about acentral longitudinal axis of the separator, and a second group of theapexes extend inwardly toward the central longitudinal axis of theseparator.
 9. The method of claim 8, wherein said separator comprises alength, said uprights are generally parallel to one another throughoutsaid length, and said apexes extend at an angle to the uprights.
 10. Themethod according to claim 8, wherein said uprights are generallyparallel over an entire length of the separator, and said apexes aredefined by struts that extend at an angle from their attachment pointsto the uprights until they meet a strut extending from an oppositedirection.
 11. The method of claim 8, wherein said second group ofapexes is defined by pairs of opposing apexes coupled one to another.12. The method of claim 11, wherein said pairs of opposing apexescomprise apex extensions and said apexes are coupled to one another viasaid apex extensions.
 13. The method of claim 8, wherein said uprightscomprise a length and some of said apexes extend from a positionintermediate said length.
 14. The method of claim 8, wherein saidseparator element is mounted to said elongate member via one or more ofsaid uprights.
 15. The method of claim 8, said separator furthercomprising a third group of apexes attached at their proximal ends todistal ends of a pair of uprights and at their distal ends to theproximal ends of an axially adjacent pair of uprights.
 16. The method ofclaim 8, wherein said separator comprises a circumference, a proximalset of apexes and a distal set of apexes oriented at roughly ninetydegrees around said circumference to said proximal set of apexes. 17.The system of claim 8, wherein said separator comprises a circumferenceand a series of apexes and wherein each apex is oriented at roughlyninety degrees around said circumference to an adjacent apex.